August 23, 2002
Team Scales Back CONTOUR Monitoring
Continual monitoring for signals from the CONTOUR spacecraft has been
scaled back. When communications from the spacecraft ceased on Aug. 15,
the mission entered "emergency" status, making it eligible for
round-the-clock coverage from NASA's Deep Space Network (DSN) antenna
stations.
Now, nine days after their last contact with the solar-powered probe, the
CONTOUR mission team says it's time to move on. "Given the disappointing
circumstances, it was time to scale back our monitoring," says Mission
Director Dr. Robert Farquhar, of the Johns Hopkins University Applied Physics
Laboratory. "We don't want to take DSN time that could be used more
effectively by other missions."
Mission operators are now listening for a signal just once a week, for
approximately 8 hours each time. Yesterday, for the first time since Aug. 15,
they started sending commands and will continue to do so during each of the
contact attempts. The commands are designed to configure the spacecraft for
active communication in case commands that are part of onboard autonomy
did not do so already.
The reduced monitoring schedule will continue until early to mid-December.
Then, for 2-3 days, the Earth will be near the center of the pancake
(multidirectional) antenna's beam width. This will be the best alignment of
spacecraft and Earth since the anomaly and the best chance the team will
have for making contact.
For a look at CONTOUR's antenna configuration, visit:
http://www.contour2002.org/overview2.html.
August 21, 2002
Six Days and Still No Signal
After six days, the Mission Operations team has yet to hear a signal from
the CONTOUR spacecraft.
Two objects, believed to be spacecraft segments, were detected Aug. 16, the
day after the solid rocket motor burn, and a third more distant object has
since been found. The objects are now more than 2 million kilometers from
Earth, traveling at a steady 6.1 kilometers per second (3.8 miles per second
or 13,600 miles per hour). They remain on a trajectory predicted by early
observations; although they have now traveled so far from the Sun and Earth
that more observations are unlikely.
If the spacecraft is still capable of operating, by Thursday, Aug. 22, it will
have completed the first cycle of having each of its two transmitters attempt
to send a signal through each of three antennas. Near continuous monitoring
for CONTOUR continues through Sunday. After that, efforts will be scaled back
to once a week - a schedule that will be maintained until early December
when the spacecraft will come into a more favorable angle for receiving a
signal from Earth. Deep Space Network coverage will extend through this
weekend.
As far as contacting the spacecraft this week, Dr. Robert Farquhar, CONTOUR
mission director from the Johns Hopkins Applied Physics Laboratory says,
"We know there's not much room for optimism through this week. Even the
second week of December, when we have our best shot, chances are small.
But it's still worth monitoring."